If any one principle provides the underpinning for smart growth, its density  putting multistory homes around rail stations, on bus corridors and at the heart of urbanized areas.

So why are so many smart-growth advocates avoiding density in their own lives?

Take Henry Cisneros, a board member with Smart Growth America. The onetime head of the federal Department of Housing and Urban Development came to Los Angeles a decade ago to work for the Spanish-language channel Univision  and immediately found a home in the plush, gated community of Bel Air Crest.

Cisneros, who now runs a company that builds entry-level housing, says that when his family moved, it was thinking heavily about crime  the 1997 North Hollywood bank shootout and the slaying of Ennis Cosby, the son of actor Bill Cosby. He also insists that he was not the driving force behind the decision on where to live.

Its the place my wife found, he says. We didnt know the community very well. Its what she chose, and given that I traveled a lot, and we did not know L.A., I felt it was the right thing to do by the family at the time.

Cisneros now splits his time between L.A. and San Antonio, leaving his daughter and son-in-law as the main occupants.

Many other high-density housing advocates have also avoided the multistory lifestyle they say Los Angeles so desperately needs.

Take developer Nick Patsaouras, a onetime board member with the Metropolitan Transportation Authority who heads the firm Polis  Greek for city. Patsaouras, who designs apartment buildings around rail stations, lives in a single-family neighborhood in Tarzana and would need to walk one and four-fifths miles from his hillside home to find the nearest bus.

Then theres Los Angeles Planning Commissioner Mike Woo, founder of the Smart Growth China Institute, which urges the largest nation in the world to embrace sustainable transportation and urban planning alternatives instead of duplicating the mistakes of the developed world.

Woo lives on a hillside in Silver Lake where every home is zoned R-1  a planning designation meant to keep apartments and condos far away. This is one of the best neighborhoods in L.A.  other than [its lack of] bus access, he says.

Consider also Pasadena architect Stefanos Polyzoides, a guru of new urbanism, who has designed transit-oriented housing developments around the Metro Gold Line. Polyzoides lives in a leafy section of Pasadena less than a block from San Marino  which prohibits all construction of apartments. His street has not only restrictive single-family zoning but also signs that bar anyone from parking without a permit.

Polyzoides, who has not only a house but also an 83-year-old Caltech observatory on his land, gives a pithy explanation for his low-density lifestyle choice: I can afford it, he says. And (b), I think Im doing a tremendous favor to my city by adopting a historic building that I am taking care of.

Of course, theres nothing inherently bad about living in a single-family neighborhood, or an L.A. County suburb, or the Inland Empire  the archetypal center of five-bedroom homes with four-car garages. But smart growth is at its heart a movement that is asking Americans  including Los Angeles residents  to change their behavior, by giving up cars, backyards and single-family homes.

Smart growth argues that riding transit, walking to stores and  perhaps most subversive  living more closely together can be a good thing.

So how can you sell people on a product that you wont buy yourself? Even worse, how can you convincingly sell a product that you think only the poor, people with no other options, should buy?

Density brings people together, for better and for worse, in four-story apartments and 80-unit condo complexes. Zoning, both good and bad, separates them. In Los Angeles, living in an R-1 neighborhood frequently means joining the elite. Nothing is more sacred in L.A. politics than the voters in R-1 neighborhoods.

That might explain why two-thirds of the Los Angeles City Council live in single-family homes, from Councilman Tom LaBonge, who lives in Silver Lake, to Councilman Jack Weiss, whose family resides in Bel Air. Councilman Ed Reyes, who complains more than anyone about the effect of zoning on Los Angeles, lives in Highland Park in an R-1 neighborhood.

Reyes said he recently thought about living in a high-rise, but his wife wouldnt go for it.

Similarly, seven out of nine citywide planning commissioners  charged with fulfilling Mayor Antonio Villaraigosas vision of elegant density  live in single-family homes, most of them in highly restricted R-1 neighborhoods. That group ranges from Woo to transportation planner Diego Cardoso, who serves as the Metropolitan Transportation Authoritys representative at Rail-Volution, a smart-growth group trying to create transit-oriented development.

Cardoso lives in an R-1 section of Westchester, a neighborhood so far from MTA headquarters that he must drive a car to his office. Patsaouras, who has a large bus plaza near Union Station named after him, commutes daily from his home in Tarzana to his office downtown. But he insists that his family takes public transportation to heart, since his wife rides transit to her own downtown job and his son takes the bus to UCLA. Im very proud, he declares.

Much more typical is Jane Usher, the Planning Commission president, who lives in tree-lined Windsor Square. Usher, whose commission is pushing new transit-oriented development, has not taken a bus in three years  and when she did, it was in London.

Usher describes her neighborhood, a place with plenty of R-1 protections, as a peaceful oasis. But the Villaraigosa appointee also argues she wont be in that neighborhood forever, that one day she will move into the housing she is currently working to create.

Im absolutely expecting that I will reach a point in time that I will want to live in multiple-density housing, she declares. This has been a delightful place to raise two little boys, but I do not think it is the only solution for me.